Overview#LDAP ping is a Microsoft Active Directory a specific Lightweight Directory Access Protocol (LDAP) or Connection-less Lightweight Directory Access Protocol (CLDAP) search that returns information about whether services are live on a Domain Controller (DC).
This is typically performed by the Local Netlogon service after the Locating the Domain Controller Candidate and the Microsoft Windows Clients use the logic defined on the for 188.8.131.52 Ping the Candidate Domain Controllers for "Liveness" and Capability Verification Using LDAP Ping Mechanism
(&(DnsDomain=abcde.corp.microsoft.com)(Host=abcdefgh-dev)(User=abcdefgh-dev$)(AAC=\80\00\00\00)(DomainGuid=\3b\b0\21\ca\d3\6d\d1\11\8a\7d\b8\df\b1\56\87\1f)(NtVer=\06\00\00\00))but it appears the Host and DomainGuid are not required.
(&(DnsDomain=EXAMPLE.COM)(NtVer=\06\00\00\02))Returns some value for the Netlogon attribute.
The first 4 bits of the first byte of the NtVer value generates four different replies (\01\00\00\00, \02\00\00\00, \04\00\00\00, \08\00\00\00) but the author of this paragraph has only ever observed a value of \06\00\00\20. The mechanics behind these bits is not known but the structures seem to correspond to Netlogon mailslot operations.
Specifications#Microsoft has specifications available in the MS-ADTS document.
Microsoft Active Directory encodes the results of an LDAP SearchRequest performed over UDP in the same manner as it does a search performed over TCP.
More specifically, as one or more SearchResultEntry messages followed by a SearchResultDone message, as described in RFC 2251.
More Information#There might be more information for this subject on one of the following:
- Active Directory Site
- Connection-less Lightweight Directory Access Protocol
- How Domain Controllers Are Located in Windows
- LDAP ping
- Netlogon attribute
- Web Blog_blogentry_190516_1